The slideshow should adapt to the height of your images. They are set to the size in the functions.php file for the imgSize “featured”. You’ll need to change the size there then re-save that file onto your server. Then regenerate the image you’ve already uploaded with: http://wordpress.org/extend/plugins/regenerate-thumbnails/

To get the slideshow to start @ the set height (instead of adjusting when the first image loads) i changed the slideshow CSS file to the same height i set in the functions.php file. That won’t break anything else i hope ?

Change the height value to the new height you are forcing the slideshow to and set crop true. Then save the file back on the server and your new images you upload will be saved to that size. If you want your old posts to use these settings, you’ll need to use: http://wordpress.org/extend/plugins/regenerate-thumbnails/